3,417 research outputs found

    Small unmanned airborne systems to support oil and gas pipeline monitoring and mapping

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    Acknowledgments We thank Johan Havelaar, Aeryon Labs Inc., AeronVironment Inc. and Aeronautics Inc. for kindly permitting the use of materials in Fig. 1.Peer reviewedPublisher PD

    From Monomials to Words to graphs

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    Given a finite alphabet X and an ordering on the letters, the map \sigma sends each monomial on X to the word that is the ordered product of the letter powers in the monomial. Motivated by a question on Groebner bases, we characterize ideals I in the free commutative monoid (in terms of a generating set) such that the ideal generated by \sigma(I) in the free monoid is finitely generated. Whether there exists an ordering such that is finitely generated turns out to be NP-complete. The latter problem is closely related to the recognition problem for comparability graphs.Comment: 27 pages, 2 postscript figures, uses gastex.st

    Measuring apoptosis at the single cell level

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    The use of live cell microscopy has made a number of contributions to the study of apoptosis. Many of the tools and techniques are available that allow us to image the key events that occur during cell death including mitochondrial outer membrane permeabilization, mitochondrial transmembrane potential changes, translocation of Bcl-2 family members, caspase activation, phosphatidylserine flip and plasma membrane rupture. We discuss these techniques here and highlight the advantages and drawbacks of using such approaches to study apoptosis. (C) 2007 Elsevier Inc. All rights reserved

    “Need to know” and the right temporal lobe: Impaired access to semantic knowledge in acquired obsessive-compulsive disorder?

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    Introduction : Idiopathic obsessive-compulsive disorder (I-OCD) has been linked to abnormalities in corticostriatal circuits. Few studies have examined if the same structures are also responsible of acquired OCD (A-OCD) or if damage to anatomically-connected brain regions (e.g., temporal lobes) are also implicated in its pathogenesis. Additionally, there are some discrete obsessive-compulsive (OC) symptoms that by virtue of their presumed low occurrence and difficultly of categorization have received less attention. Amongst these, one intriguing and potentially severe type of obsessive thinking is the so-called “need to know” (NtK), a strong drive to know and obtain given information. In some patients this specific symptom, presumably resulting from impaired access to conceptual knowledge for specific verbal information (proper names, names of places), may be the principal or major feature of OCD symptomatology. We here report the cases of two male patients who developed “NtK” as the only OC symptomatology in association with malignant neoplasms involving the right temporal lobe and connected corticostriatal circuits. Methods : We used Tractotron and Disconnectome map softwares in order to identify the regions of white matter damage overlap across both patients and the proportion of damage (lesion load) of each tract of interest for each patient. We quantified the severity of the disconnection by measuring the proportion of each tract of interest to be affected by each patient®s lesion by using Tractotron software. Additionally, Positron Emission Tomography was used in order to study metabolic abnormalities. The tracts of interest were: the uncinate fasciculus, the anterior commissure, the anterior thalamic radiations, the inferior fronto-occipital fasciculus and the inferior longitudinal fasciculus. Results : There was a high overlap across brain lesions in patients 1 and 2. There was also a high overlap between areas that were affected (disconnected) due to the lesion. As expected, all the a priori selected pathways in the right hemisphere were affected since they cross the anterior part of the temporal lobe. Disconnection maps and metabolic changes in our patients suggest that the expression of OC symptoms underpinned by a semantic deficit due to right temporal damage is secondary to involvement of the uncinate fasciculus linking the temporal pole with the orbitofrontal cortex. Discussion : Data from the present study concur with previous research on A-OCD and current findings in I-OCD which suggest that the temporal lobes participate in the phenomenological expression of OCD. Also, patients with lesions in the anterior temporal lobe are prone to show a specific “Need to Know” symptoms phenomenologically similar to patients with semantic dementia in later stages. The expression of OC symptoms underpinned by a semantic deficit because of anterior right temporal lobe lesion, are due to a disconnection of the uncinate fasciculus and the orbitofrontal cortex. Further research about the neurological underpinnings of specific OCD subtypes, its evaluation and treatment, are essential. References : Berthier ML et al. Neurology. (1996) 47: 353–61. Huey E et al. J Neuropsych Clin Neurosci (2008). 20(4):390-408 Keywords : Emotions & Social Cognition; patients; single case study; adults; psychiatric; lesion mapping, behavioural.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

    What traits underpin the successful establishment and spread of the invasive water bug Trichocorixa verticalis verticalis?

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    The introduction of exotic species has a major impact on a wide range of ecosystems, especially in aquatic ecosystems. Trichocorixa v. verticalis (Fieber, 1851), an euryhaline aquatic hemipteran native North America, has occurred as an exotic species in the Iberian Peninsula since at least 1997. In this study, we compared several physiological and biological traits (salinity tolerance of the different developmental stages, thermal tolerance, fecundity, and dispersal ability) in the alien species and three native, syntopic corixidae species (Sigara lateralis, Sigara scripta, and Sigara selecta), to determine which traits may explain its invasion success. Trichocorixa verticalis was the species most resistant to high conductivity at the egg stage, while S. selecta showed the highest halotolerance as adults. The invader had the highest upper thermal limit and a much higher fecundity than Sigara species. Wing morphometry suggested that T. verticalis may be a stronger flier than the native species. Our findings provide an example of how functional and ecological niche interactions among alien and native species can help predict impacts of invasion on aquatic communities.Peer Reviewe

    Functional aspects of root architecture and mycorrhizal inoculation with respect to nutrient uptake capacity

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    ACESSO via B-on: http://dx.doi.org/10.1007/s00572-003-0254-5The aim of this research was to investigate theeffect of arbuscular mycorrhizal (AM) colonisation onroot morphology and nitrogen uptake capacity of carob(Ceratonia siliqua L.) under high and low nutrientconditions. The experimental design was a factorialarrangement of presence/absence of mycorrhizal fungusinoculation (Glomus intraradices) and high/low nutrientstatus. Percent AM colonisation, nitrate and ammoniumuptake capacity, and nitrogen and phosphorus contentswere determined in 3-month-old seedlings. Grayscale andcolour images were used to study root morphology andtopology, and to assess the relation between rootpigmentation and physiological activities. AM colonisationlead to a higher allocation of biomass to white andyellow parts of the root. Inorganic nitrogen uptakecapacity per unit root length and nitrogen content weregreatest in AM colonised plants grown under low nutrientconditions. A better match was found between plantnitrogen content and biomass accumulation, than betweenplant phosphorus content and biomass accumulation. It issuggested that the increase in nutrient uptake capacity ofAM colonised roots is dependent both on changes in rootmorphology and physiological uptake potential. Thisstudy contributes to an understanding of the role of AMfungi and root morphology in plant nutrient uptake andshows that AM colonisation improves the nitrogennutrition of plants, mainly when growing at low levelsof nutrients

    PP-Wave Light-Cone Free String Field Theory at Finite Temperature

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    In this paper, a real-time formulation of light-cone pp-wave string field theory at finite temperature is presented. This is achieved by developing the thermo field dynamics (TFD) formalism in a second quantized string scenario. The equilibrirum thermodynamic quantities for a pp-wave ideal string gas are derived directly from expectation values on the second quantized string thermal vacuum. Also, we derive the real-time thermal pp-wave closed string propagator. In the flat space limit it is shown that this propagator can be written in terms of Theta functions, exactly as the zero temperature one. At the end, we show how supestrings interactions can be introduced, making this approach suitable to study the BMN dictionary at finite temperature.Comment: 27 pages, revtex
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